A component such as a retractor of a seat belt device may be mounted in an upper portion of a seat back frame of a vehicle seat. In a configuration described in JP-A-H9(1997)-254689, in a wide seat back, a bracing reinforcement panel is connected with the panel-shaped seat back frame, and the retractor is mounted in the upper portion of the bracing reinforcement panel. The bracing reinforcement panel can be provided in any position of the upper side of the seat back frame in a width direction. Thus, the increase in the thickness of the seat back can be suppressed while seating comfortableness is not deteriorated when the retractor is provided in a position where a seating pressure of a seated occupant is not applied.
On the other hand, in the vehicle seat including the above-described wide seat back, three vertical frames which extend vertically may be provided. In such a type of seat, a bracket may be provided in an inner corner portion of a connecting part between any vertical frame and an upper frame extending in a lateral direction, and the retractor may be mounted therein. In such a case, it is preferable that the retractor is provided as far from a seating surface as possible, so that the seating comfortableness is not deteriorated while the increase in the thickness of the seat back is suppressed.